denton
Member
It's not so hard.
Gauge factor is easily known to 3-4 significant digits. Young's modulus for steel is obtainable to 3 significant digits. The ID and OD of the chamber are easily obtained to 3 significant digits. Gain of the amplifier chain is easily determined to 4 significant digits. The Hoop Strain is well understood, and validated.
If you have all that, your resulting pressures will be accurate (calibrated) to at least a percent or two, and that is all that is required to be useful.
The random error in both piezoelectric and strain systems limits calibration to no better than about half a percent. Regardless of what we do, we aren't going to do better than that with existing equipment.
For an example simpler than pressure, consider measuring speed. There are no standard artifacts to compare with. We have standards for distance, and standards for time, and from those, by computation, we get calibrated chronographs.
Gauge factor is easily known to 3-4 significant digits. Young's modulus for steel is obtainable to 3 significant digits. The ID and OD of the chamber are easily obtained to 3 significant digits. Gain of the amplifier chain is easily determined to 4 significant digits. The Hoop Strain is well understood, and validated.
If you have all that, your resulting pressures will be accurate (calibrated) to at least a percent or two, and that is all that is required to be useful.
The random error in both piezoelectric and strain systems limits calibration to no better than about half a percent. Regardless of what we do, we aren't going to do better than that with existing equipment.
For an example simpler than pressure, consider measuring speed. There are no standard artifacts to compare with. We have standards for distance, and standards for time, and from those, by computation, we get calibrated chronographs.
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